Currently, when paying with a gift card doesn't work ideal. There are two issues we're facing:

- Available amount on gift card has to be checked with a click of a button
- The amount of the basket is entered as the amount payable.

This causes the following issues:
One click more is necessary to validate how much is available - it would be great if this information is shown automatically
If the amount due exceeds the available amount on the gift card, the amount has to be entered manually

This would lead to the following change:
Automatically show the available amount upon entering a gift card code
Preset the amount payable with either the amount due or the available amount on the gift card, whichever is higher